The present invention is directed to a device for sealing an annular gap located between a laterally closed bearing bush of a universal joint and a pin of a spider inserted into the bush. The device axially supports cylindrically shaped bearing members located within the annular gap. A stop plate is located at one end of the bearing members and a seal is spaced from the stop plate and provides a sealing action between the inner wall of the bush and the circumferentially extending outer face of the pin. A support member acts as a carrier for the seal and is located spaced between the outer face of the pin and the inner wall of the bearing bush.
In a known design disclosed in DE-PS No. 31 18 430, a seal carrying the stop plate is connected to the bearing bush. The connection is provided by resilient circumferential parts and by engagement into a groove in the inner wall of the bearing member.
Sealing relative to the spider is afforded by sealing lips. The sealing lips open under the pressure of the lubricant, accordingly, the seal is intended for use in a universal joint to which lubricant can be added. This design has the disadvantage that with higher axial forces exerted by the bearing members on the stop plate and the seal connected to it, the seal may be pushed out.
Therefore, the bearing members may run against the angular transition face of the spider and lead to jamming and destruction of the bearing.
Another disadvantage is that to insure a firm arrangement of the seal stop plate in the bearing bush and accurate positioning, it is necessary to provide a stepped bore which tends to weaken the bearing bush and the supporting forces which, to insure satisfactory holding in the bearing bush, require the bush to have a corresponding thickness which cannot be sufficiently accommodated. Still another disadvantage is that during assembly the free ends of the sealing lips face away from the slipping-on direction.
In DE-AS No. 25 56 769, there is a known seal firmly arranged on the pin. The bearing members are supported directly against the seal. The disadvantage in this arrangement is that the seal is capable of accommodating only low axial forces from the bearing members.
In DE-GM No. 86 16 597, there is another known prior art device which provides for a separate arrangement of a stop plate axially held relative to the bush by a securing ring. This arrangement cannot prevent axial movement of the bearing members and loading of the seal. Furthermore, it influences the axial length or limits the assembly length for the bearing members.
It has been found that as a result of production-related play, the bearing members when torque loaded are inevitably moved into an inclined position.
Such inclined position produces axial forces moving the bearing members in the direction of the open end of the bearing bush. These axial forces exert a load on the seal and may cause it to be displaced from its seat or may cause leakage. Either effect leads to a reduction in service life or to an early failure.
In still another known arrangement in DE-OS No. 34 19 111, the seal is provided with an angle collar supported by a holding ring relative to a groove in the bearing bush. The disadvantage of this arrangement is that the angle collar must be precision manufactured to afford a firm fit. If the over-dimension selected for achieving a firm fit is too great, additional loads will be exerted on the relatively thin-wall bearing bush. If the over-dimension is too small, there is the risk that the seal turns relative to the bearing bush whereby accurate sealing conditions no longer prevail. Moreover, there is no possibility of achieving a seal between the outer face of the angle collar and the inner wall of the bearing bush with the risk of lubricant escaping from or penetrating into this region which adversely affects the holding function.
Finally, DE-OS No. 20 47 420, proposes an angle collar embedded in the seal. Axial support is provided in an elastic manner by the sealing material itself, so that again there is the risk of the bearing members assuming an inclined position.